In a process for manufacturing a semiconductor device, various types of treatment apparatuses (semiconductor manufacturing apparatuses) are used to perform treatments such as oxidation, diffusion and chemical vapor deposition (CVD) on an object to be treated, such as a semiconductor wafer. It is known that one of the various types of treatment apparatuses is a batch-type heat treatment apparatus, such as a vertical heat treatment apparatus, capable of simultaneously performing a treatment, such as a heat treatment, on a plurality of objects to be treated.
Such a conventional heat treatment apparatus generally has a process chamber and a tubular heater. The process chamber accommodates a plurality of wafers to be held on boats, which are provided in multiple stages at a predetermined interval and serve as holders. The heater surrounds the process chamber. The heat treatment apparatus performs a predetermined heat treatment by causing the heater to heat the wafers. The heater includes a tubular heat insulator and a linear heat generating resistor provided on an inner circumference of the tubular heat insulator.
After the heat treatment, the conventional heat treatment apparatus discharges an atmosphere present in a space existing between the heater and the process chamber and introduces a cooling fluid (such as air) into the space to forcibly cool the heater, in order to rapidly reduce the temperatures of the wafers thereby accelerating the treatment and improving the throughput of the treatment. One of such conventional heat treatment apparatuses (hereinafter called the former conventional heat treatment apparatus) has a flow path structure. In the flow path structure, a cooling fluid is distributed from a common air supply duct to a plurality of distribution tubes, each of which then distributes the cooling fluid to outlets (nozzles) through flexible tubes. The air supply duct extends in a vertical direction. The distribution tubes are provided on the outer circumference of the heater and at vertical positions different from each other. The outlets are provided in a heat insulator and at vertical positions. The outlets are arranged in the circumferential direction of the heat insulator at an appropriate interval. The outlets extend toward a central axis of the heat insulator.
In another one of conventional heat treatment apparatuses (hereinafter called the latter conventional heat treatment apparatus), a cooling fluid is supplied from an intake tube through an introduction valve to an annular intake manifold provided under a heater, as described in Patent Document 1. The cooling fluid is distributed from the intake manifold to a plurality of intake ducts extending in a vertical direction and arranged on the outer circumference of the heater at a constant interval. The cooling fluid is then distributed from each of the intake ducts to outlets (intake communication flow paths) extending through a side wall of the heater in a horizontal direction and toward a central axis of the heater and provided in top and bottom stages.
Patent Document 1: JP-A-2000-195808
In the former conventional heat treatment apparatus, however, it is necessary that an adjustment valve or an adjustment damper be provided for each of the distribution tubes in order to adjust the rate of the reduction in the temperature of each part of the heater. The fluid path structure for forcibly cooling the inside of the heater with air is complicated. The number of parts necessary for the structure is large. This leads to an increase in the cost and difficulty in sealing. Since the flexible tubes branched from the distribution tubes are connected to the outlets (nozzles) in the flow path structure, the positions and the number of the outlets and the like are limited, and the degree of freedom of the outlet design is low. In the latter conventional heat treatment apparatus, because the positions and the number of the outlets and the like are limited due to the intake ducts, the degree of freedom of the outlet design is low. It is difficult to adjust the amount of the cooling fluid to be supplied to each of the outlets and used to adjust the rate of the reduction in the temperature of each part of the heater.